Fix compilation failure because of changes in ndn-cxx library

This commit also updates ChronoSync submodule for the same reason.

Change-Id: Ie5e6a4398cf05c8be12ea533503c31eb73e61bbd
Refs: #2996
diff --git a/src/chatroom-info.hpp b/src/chatroom-info.hpp
index ac0d602..dca4090 100644
--- a/src/chatroom-info.hpp
+++ b/src/chatroom-info.hpp
@@ -97,7 +97,7 @@
 private:
   template<bool T>
   size_t
-  wireEncode(ndn::EncodingImpl<T>& block) const;
+  wireEncode(ndn::EncodingImpl<T>& encoder) const;
 
 private:
   mutable Block m_wire;